U.S. Pat. No. 3,689,855 teaches an interrogator responder arrangement that is capable of handling random orientations between the interrogator and the responder for use in applications such as the tracking of guards, watchmen and executives in industrial plants wherein each person carries a small, inexpensive non-radiative passive responder. Interrogators are positianed at various fixed locations throughout the plant. In addition, this interrogator and passive responder arrangement could be used for the handling of luggage and cargo in airport terminals and freight terminals. In addition to a responder tag that is attached to each individual piece of luggage at the check-in station or at the ticket collection station at an airport terminal, a second responder tag having a code generation capability that provides the same code as the first responder, or bears a known correspondence to that one, is given to the passenger, and the passenger can insert the second tag into the baggage request station automatic handling equipment to detect the paticular code on the tag and locate the passenger's luggage.
Other applications are directed to the use of tag and reader systems for the handling and tracking of livestock. U.S. Pat. No. 4,262,632 teaches an electronic livestock identification system containing a capsule or pill having an electronic transmitter which is uniquely coded to broadcast a series of electronic pulses from each animal in which it is internally implanted. An associated interrogator receiver unit, which is preferably situated externally of the animal, may be used for sensing and appropriately utilizing the electronic pulses to identify the animal. Although the capsule may include a power supply, it is preferably a passive storage element to which power may be induced from the interrogator.
International Application Number PCT/US87/00415 is directed to a syringe implantable identification transponder which is syringe implantable into an animal and provides identification of the specific animal when the transponder is interrogated. This transponder has particular application to the identification and monitoring of migratory waterfowl and other small animals such as fish.
Given the limitations and relatively high costs of these tracking and locating systems, an improved method for tracking and locating objects that is less expensive is desired. Suitable methods would permit a consumer to easily tag desired objects, to identify the importance of those objects, and to assign any necessary information related to those objects. In addition, it is desired to be able to track those objects across greater volumes of space and not to confine the locating and tracking of those items to fixed areas where scanners are located.